The aim of the study is: a) to determine the mechanism of insulin resistance in obese subjects. NMR studies in six healthy women showed an improvement of muscle glycogen synthesis due to a defect in glucose transport/phosphorylation which was partly reversed with weight loss; b) to evaluate differential insulin resistance in African-American and Caucasian obese women. To date fourteen African-American women have been studied. Preliminary data suggests substantial differences in insulin sensitivity for suppression of free fatty acids and glucose uptake in obese African-American women. The data for protein turnover and antilipolysis are being analyzed. At present time, Caucasian women are being studied.